HS4Air
HS4Air is a proposed 140km rail line from the HS2 line near Denham to Ashford International via Heathrow and Gatwick Airports. It was the similar scheme to even extend the HSR from Jurong East to Changi Airport via the city. It would form as a direct link between the HS1 and the HS2 which was scrapped in 2014 and also provide a link to Heathrow (scrapped in 2015) as well as Gatwick. A fifth of the line is to be in tunnel and could link with the Great Western Main Line. It would cost $10 billion to build and around 40% of the route is to be reusing existing network rail tracks. It was planned to be opened in the late 2020s, and will consist of the three stations. The proposed line would connect the planned High Speed 2 line to the High Speed 1 line via a high-speed route running south of London, and would form a direct rail link between Heathrow and Gatwick airports. Background The first high-speed railway line to be built in the United Kingdom was High Speed 1 (HS1), the route connecting London to the Channel Tunnel, which opened 2003−2007. A second high-speed line named High Speed 2 (HS2), which will initially run between London and Birmingham, is planned to open in 2026. A proposal to build a direct connection between HS1 and HS2 in central London was dropped from HS2 construction plans in 2014 due to cost and the impact on the London suburb of Camden. The HS2 plans also included a connection to Heathrow Airport at Heathrow Hub railway station, but that link was dropped in 2015. A number of other schemes have been considered to create a rail link Heathrow and Gatwick airports, collectively dubbed "Heathwick". Planned route The proposed line would leave the HS2 line at a junction near Denham in Buckinghamshire, and then run on a route curving south-east of London, partly parallel to the M25 motorway, with stations at Heathrow Airport and Gatwick Airport. It would then head eastwards across Kent using the existing upgraded South Eastern main line via to join HS1 at a junction at . The link between HS1 and HS2 would allow high-speed trains to travel directly between regional cities in Great Britain and destinations in Continental Europe. A fifth of the line is to be in tunnel in order to mitigate the environmental impact on sensitive rural areas such as the North Downs. It is also proposed to construct a link with the Great Western Main Line. It would cost £10 billion to build and around 40% of the route would reuse existing tracks; the proposals include upgrades at and stations. The scheme envisages a 15-minute transfer time between Heathrow and Gatwick, allowing the two airports to operate jointly as an airline hub. Fast connections between the airports and Birmingham, Manchester and Cardiff are also proposed, and the proponents of the scheme claim that it will alleviate pressure on transport within London by reducing the need for air passengers to travel through the city. The scheme has also been linked to proposals to re-open Manston Airport in Kent, which could be connected to the line via . Government approval The scheme is currently at the proposal stage and has not been approved by the Government. Expedition Engineering's plans are due to be submitted to the Department for Transport by the end of July 2018 as part of the Government's plans to encourage private investment. The DfT will respond in the autumn.